Electronic control system



Feb. 10, 1948.

S. D. EILENBERGER ELECTRONIC CONTROL SYSTEM Filed Sep'h. 22, 1943 3 SheetS-S'neet l Planu Feb' 10, 1948' s. D. EILENBERGER ELECTRONIC CONTROL SYSTEM Filed Sept. 22, 1943 n lNvENToR FIC:

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F'IGDE) s. D. ElLL-:NBERGER ELECTRONIC CONTRL SYSTEM Feb. 10, `1948.

Filed Sept. 22, 1943 3 Sheets-Sheet 3 31-8 n le] D. EL ten bev'ge jr' Patented Feb. 10, 1948 ELECTRONIC CONTROL SYSTEM Stanley D. ,Eilenbergei Kenosha, Wis., asslgnor,

by mesneassignments, to Chicago (Join Machine Co., a corporation of Illinois :Application September 22, 1943, Serial No.'5(l3,425

' 2 Claims. (Cl. 235-952.)l V

-This inventionrelates to an electron switch and in particular to such a switch for 'use in amusement games. In such'games it is often desirable to energize a Circuit such as, for example, closing a re1ay,upon'the passage of an object, such as,'forexample, a playing'ball, where-such playingball may be'metallic or non-metallic.

z- In the majorityof such applications mechanical switches are satisfactory, and n'umerous such devices are in' common use. An' alternate'method ofaccomplishing the 'desire'd result,`` i. e., energizing a Circuit by the pas'sageroffan'object such as a playing ball, is by theuse of'photoelectric cells and a light beam; where the passage of the ball interrupts the-light beam 'an'dprovides vthe necessary impulse to energize a registration circuit. This photoelectric 'method has been used to some extent in'amusenient games. However, there are certain disadva'ntages to the photoelectric method, 'one of which 'isathat ambient light must be compensated' for if'the device is to be sensitive under all conditions of ambient light. This is particularly so when an 'amusement device is placed in such a 'position that it is exposed to strong daylightduring a portion of the time it is in use, and operated in reduced illumination of artificial source at other times;

As a practic'al mattenany` such triggering device used in an amusement game 'must be -reliable under all conditions and' not subjectto Variation by such conditions as ambient-light. A-further ymethod which has 'been' considered for use as a triggering device in lan*amusement'game'is the so-'called capacity controlV circuit'. While such devices can be made self-compensating and relatively sensitive to the passage of the playing ball, extreme accuracy of construction is necessary in order to permanently maintain such a capacity controlled circ'uit in a Sensitive condition, :and an additional disadvantage is'thatall'such capacity controlled circuits arelsensi-tive to body capacity, i. e., any external capacity to ground.

17 It is very difficult, if not simpossible, -to= so'de'- sign a capacity control triggering device so that it'is not aifected by external capacity to ground, provided such external capacity to ground and in particular body capacity, i. e., placing the hand of the player near the capacity control electrode or antenna, is larger than the capacity change produced by the passage of the playing ball.

For practical reasons this body capacity is always larger than the capacity change produced by the passage of the playing ball, and for this reason capacity control circuits are not practical for use in amusement games, without resorting to special precautions, .such as shielding electrodes or providing a large vdistance between the exposed electrode or antenna and the ,nearest position of the player. In general, it is impossible to maintain a distance of `more than several inches between the exposed electrode or antenna and the nearest position of theplayer and, Vwhile shields may be interposed between the exposed electrode or antenna and the nearest position of the player, these shields act to partially obscure the playing board and are therefore undesirable. This invention discloses-a method of triggering a control circuitfinv an amusement device where the principle Iof operation is in part based on capacity change., In. practice the control circuit herewith'disclosed is .economical to manu- 'facture and absolutely vreliable;l It is not affected eration will not occur fromfbody capacity effects.

^ As previously mentioned, amusement games 'have been operated to-a large extent with mechanical switches. Some Vof these switches have been perfected to a high degree, so that they make contact withl very i slight. pressure, but .regardless ofy how slight-the pressure required to operate 'such a mechanical switch, there are con-: ditionszunder whichnozmechanical switches are satisfactory. By way-'ofV one specificV example, U. S. Patent Number 2,31%,169 to Larock describes a ltwinhockey game which .is operated by two players. Mechanicalrswitches are used `throughout in this game. .A totally. different effect could be achieved in sucha game if it were possible to record the passage, of the; playing ball as it crosses a given point :onthe playing board. For example, atwintennis game could be constructed insuch a mannenthatthe score was dependent on the number of times each player's ball crossed af center lineonvthe playingV board, where said center line was analogousto the net in ordinary lawn tennis. For this`V ,purpose mechanical switches are not satisfactory. This is so because, regardless of how light a pressure may be required to operate such a switch, it must of necessity, slow down the playing ball and it may used in combination with an especially designed electrode so that the degree of feedback is increased by the passage of any object, such as, for example, the playing ball normally associated with amusement games of the class herein referred to, this increased feedback producing a direct current pulse which is further used to triggel' a gas fille'd discharge tube which in turn operates an associated registration means to suitably register the passage of the playing ball. Triggering and subsequent registration may be secured by the passage of any object through the electric field associated with the electrode. While the playing ball is normally metallic, for purposes of the present invention, metallic .playing balls are not necessary, as trigger action may be secured by the passage of :any object, metallic or non-metallic. By way of example, the playing ball may comprise a steel ball as normally used, a glass marble or a plastic ball. Similar trigger action will be secured regardless of the material of whichithe' -playing ball is made.

The primary object of thisiinvention is to provide a control or trigg'ering device for use in an amusement game, where said control device is not 'dep'endent on mechanical movement of any kind and where said control device is insensitive to any external influence 'and'where the electrode associated with the said control device is 'so arranged as to present no mechanical obstacle to the passage of the playing ball and where said 'control device may be triggered only by 'the pas- Sage of the playing ball.

A further object of this invention is to provide "two or more 'such control devices together with their associated electrodes and re'gistratioh means so that the direction of Atravel of 'the playing ball may be recorded.

This invention is a modified form of the inven'tion disclosed'by my co-pending patent applications g entitled "Electronic measuring instrument," filed September V1-7, 1943, Serial Number 502,843, now vPatent No. 24283700, and Electronic control device, filed September 20, 1943, Serial Number 503,163, both 'of these inventions utilizing the feedback principle 'in combination with a shielded electrode of 'special'd'esign The present invention deals 'with vmodifica'tions and improvevments of such a nature that the principl'es Vdisclosed by the aforemention'ed'patent applications 'may be utilized as an electronic control switch v'reference should be made to the abovecited applications.

It is well known in the art that any Vamplifier 4 willroscillate if the output of said amplifier is lcoupled to the input of said amplifier, providing sufiicient energy is fed back from the output side 'of said amplifier to the input "side of Asaid amplifier. This must always be so, irrespective of whether such feedback'is obtained capacitively, vinductively, resistively or by'other means. It is Valso well known in the'a'rt that the frequency of oscillation in this case will be determined by the vcircuit constants Aand that said frequency may be made any value desired Aby'proper selection of said circuit constants.

'As previously stated, v'niimerou's electronic measurement and control methods have been based on this feedback principle. Briefly, the present invention discloses a method of producing a feedback Voltage by the use of two electrodes, one connected to an output of an amplifier and the other connected to the input of said amplifier, said electrodes being so shielded from each other that with all circuit values properly adjusted zero or minimum oscillation occurs. For this condition, any object introduced in the electric field associated with the electrode will increase the feedback voltage.

With properly adjusted circuit values the instantaneous DJC. peak voltage produced by the passa'ge of an object through the electric field associated with said electrode may be on the order of several hundred volts. This allows the control device associated with the amplifier-oscillator to be adjusted for maximum stability at low sensitivity. For example, a gas filled discharge tube may be adjusted to operate on a voltage differential on the order of less than 1 volt, but such adjustment is critical and such a device must of necessity make use' of precision construction to maintain a fair order of stability. For example, 'the effects of temperature, voltage change, etc., must be compensated for if close regulation is desired. In the 'present invention, the arrangement is such that no D. C. control voltage is normally present on the control grid of the gas filled 'discharge tube used as the controlling means.

The passage of an object through the electric field associated with 'the control electrode may produce a voltage surge of, for example, 200 D. C. 'volts. For this condition the gas filled discharge 'tube can 'be adjusted to ionize at, for example, 25 D. C. volts. For this condition, the entire device is exceptionally stable in operation and almost totally independent of variations in voltage, temperature and other variable factors.

A further advantage of the present invention -is that the design and operation 'of the control electrode is such that it may be concealed within vthe "playin'g Iboard so that no visible registration means are noticeable to the player, such construction also having the further advantage of providing a perfectly smooth 'playing surface, lt being understood that the control electrode may alsobe so mounted as to be visible to the player without offering any obstruction to the passage of the playing ball.

This invention will be best understood in consideration of the following detailed description,

'inview of the a'ccompanying drawings forming a part of the application. Nevertheless, it is understood that the invention is not confined to the disclosure, being susceptible to such changes and 'modifications as define no material departure from the salient features of the invention as expressed in the appended claims.

In the drawings:

Figure 1, section 'A represents a suitable amlifier for use in the practice of this invention;

section B schematically represents a suitable electronic control circuit for use with the amplifier of section A; section C represents one part of the registration means normally employed in amuse-' ment devices of the class herein referred to; section D represents a partial view of the control electrode and the playing board in an amusement device.

Figure 2 represents an enlarged view of the control electrode installed Ilush with the surface of the playing board in an amusement device.

Figure 3 represents the electric field associated faccordance with u'sual practice.

with the control-electrode for acondition where 'no object is in the electric field.

'it being understood that any form of amplifier providing sufficient voltage gain may be used in the practice of this invention. I have found that a voltage gain on the order of 10,000 is practical, it being understood that any voltage gain producing the desired sensitivity may be used. Control grid 4 of vacum tube is connected to common ground terminal 24 through grid resistor 6, which may have a nominal value on the order of .5 megohm, and also by lead 39 to metallic electrode 46, connecting lead 39 being completely shielded by grounded shield V38.

VScreen resistors and 22, screen by-p'ass condensers 9 and 2|, cathode resistors 8 and 20, cath-l ode by-pass condensers 1 and |9, 'grid resistor |8, plate resistor coupling condenser 2 and bypass condenser 23 may all have a value determined by the particular type of tubes utilized for vacuum tubes I' and |3, these values being in Terminal 25 is the common B negative terminal, while terminal 26 is the B positive'terminal.

The output of vacuum tube |3 is' connected through transformer 21 to full wave rectifier tube 3|.

Transformer '21 is represented, for purposes of example, as an iron core transformer, having a primary winding 28 and a center tapped secfl "ondary winding 29+30, such transformer preferably having a stepup ratio onl the 'order of 3:1,

.or higher, it being understood that the use of'` an iron core transformer is optional. of transformer 21 will largely determine the feed- The design back frequency and, for the purposes of this invention, a medium audio frequency, such as, for

example, 4000 C. P. S., provides sufiicient sensitivity with good stability. It is understood that 'other frequencies may be used without departing from the principles disclosed by this invention.

Full wave rectifier 3| is represented as a vacuum tube, it being understood that other formsv of rectifier may also be used, and that aV half wave i rectifier may be used in place of the full wave rectifier shown. While the half wave rectifier '-will produce a somewhat higher control voltage,

'to terminalu of the secondary winding of translic electrode 4 l.

Referring now to' section D of Figure 1, where the 'playing board is represented by 43 and the playing ball'by'42, which may be considered as traveling yin the direction indicated by the arrow.

'The entire electrode assembly as represented by 'sections 44, 45, and 46 is countersunk fiush with thesurface of 'the playing board, where 46 is the input electrode, which may comprise a thin strip of metal, for example, a section having a thickness on the order of BL.- inch and a width of 1/8 inch, so mounted, that the e12- inch edge is presented at the playing surface. 44 represents 'a grounded metallic shield completely enclosing three sides of input electrode 45, and the insulation interposed between input electrode 46 and grounded metallic shield 44 is represented by the solid lines 45.

The output or feedback electrode comprises a metal plate 4| normallyrmounted under the playing board. The actual dimensions of electrode 4| are non-critical, an average width for such electrode being on the order of 1 inch. Feedback electrode 4| is also shielded on the lower side by metallicV shield 40, it being understood that metallic shield is insulated from feedback electrode 4|.

The entire control electrode structure as represented by numerals 44, 45, and 46 of section it has the disadvantage of being less reliable' at "w high playing speeds, as it is only operative every other half cycle and for that reason the fre- Aquency of osciliation must be maintained high 'enough-to provide trigger yaction at the high'est onds.

The'D. C. output voltage of rectifier 3| `is pres- 'ent across load resistor 33 which is in turn bypassed by condenser 32 and this voltage'is avail- ,able atterminals 36 and 31 with a polarity as indicated. 1

The feedback connection is shown connected D in Figure 1 is a compact assembly, which may, for purposes of example, have overall dimensions lof l/g inch wide, 1A. inch deep and a length determined by the width of the playing board, it being understood that while this electrode structure is shown as .a straight line, for purposes of example, that such electrode may be made in any desired Shape, such as, for example, semicircular, angulanzetc. A more complete description of the structure of electrode 44, 45, and 46 is given further below in connection with Figures 2 and 4.

Referring now to section B of Figure l, which represents the electronic control circuit normally .associated with the amplifier schematically illustrated by section A of Figure 1 and previously described. vIn section B, 12 represents a gas fi-lled discharge tube having a control grid 15 connected in series with condenser 13 to positive control voltage terminal 36 and a cathode 16 connected to the negative control Voltage terminal 31. Plate 13 is connected to a source of positive kvoltage V26 in series with normally closed contacts 52, current limiting resistor 69 vand'relay 10. suppressor grid 14 is biased negative in respect to cathode 16 by a source of voltage'80, having fa polarity 'as indicated. Sensitivity is controlled both by the adjustment of voltage 80 and the setting of grid resistor 11, it beingunderstood that other methods of sensi- 70 tivity control may be used.

For any given value of plate voltage Ep and any vgiven value of negative suppressor grid voltage Es, a definiteivalue of positive control grid voltage E; will be required to ionize gas filled discharge .tube 12. i

on control grid 15.

For .a condition whereno playingball is in the electric field associated with the control electrode, no positive D. C. voltage will be present Any small D. C. voltage which may result from external magnetic or electrostatic pickup, normal circuit voltage, secondary electron emission, etc., is broken by condenser IS. However, for a condition where playing ball 42 passes through the electric field associated with the control electrode, an instantaneous voltage is produced which will appear as a D. C. voltage Eg. This voltage pulse will occupy a time interval much greater than the ionization time of gas filled discharge tube T2, for any practical playing speed. For example, I have found that the circuit arrangement here given by way of example is reliable at playing speeds on the order of 40 feet per second, which is considerably in excess of playing speeds normally used.

It is characteristic of all gas filled dischargel tubes that where a D. C. plate voltage is used the grid loses control after the tube is ionized. This is so in the present'instance, and gas filled discharge tube 72 remains ionized after the control voltage Eg has returned to zero. However, ionization of gas fil-led discharge tube 12 allows the tube to draw plate current'which results in the operation of relay 10, thus closing normally open contacts 1|, which in turn energize the magnet 50 of the Stepping Switch illustrated in 'section C of Figure 1, said magnet 50 being energized from a source of voltage 48 and 49.

Referring now to section C of Figure 1, a selfinterrupting Stepping switch is illustrated. Operation of relay 70 energizes magnet 58, thus Operating armature 54 and momentarily opening normally closed contacts 52, which momentari-ly removes the D. C. voltage from the plate 13 of gas filled discharge tube 12 and restores the circuit to the standby position, ready to operate on the next impulse received by the passage of an object through the electric field associated with the control electrode.

The balance of the stepping switch illustrated by section C of Figure 1 is the form usually employed in an amusement device, where 58 is the armature fulcrum, 59 the armature, return spring, 56 the pawl associated with ratchet 60,55 the pawl spring, and 53 an insulating Stud control-` ling operation of oontacts 52. The detent is represente'1 by 5|, the wiper shaft by 51, and the wipcr arm by 6|. In part, the contacts are represented by the figures 62, 63, 64, 65, 66, 61, and 58, which are in turn connected to any denated figures.

The operation as just described requires only the use of a single electrode 44, 45, and 45, together with the associated feedback electrode 4|, where registration would be secured regardless of the direction of travel lof playing ball 42. However, it is readily apparent to those skilled in the art that two Vsuch electrodes may be used where each electrode is associated .with a separate amplifier, a Separate gas lilled tube and a separate stepping switch. This dual operation will be similar to that described for single operation, except that the operation of the first stepping switch is arranged to lock out the second Stepping switch for a period of time equivalent to the time required for the first Stepping switch to operate and release. This time isordinarily on .the order of .15 second.

If two electrodes similar to electrode 44, 45.

and 46 .and two feedback electrodes similar to electrode 4| are placed vrelatively close to each other in a horizontal plane, such as, for example, an edge to edge distance of 1 inch, for any practical condition, the playing ball will cross both electrodes inl a timeconsiderably less than .15 second. A reasonable time required for playing ball 42 to cross the 1 inch distance between two such electrodes would be on the order of .O05 second. For this condition, playing ball 42 will register on the first electrode contacted-but not on the second, but the second electrode will again be free to register in approximately .15 second. It is obvious to those skilled in the art that such an arrangement is applicable'to high speed operation where numerous playing balls are traveling in both directions, and that registration would be in accordance with the direction of travel.

Referring now Specifically to Fig, 6, the above described multiple operation is shown ndetail where electrodes 4B and 46a, 4| and 4|a represent the multiple electrode structure. A11 reference numerals are identical with those used in Fig. 1, lwith all plain numerals associated with amplifier A, control circuit B, and Stepping switch unit C, and all numerals carrying the sufiix a associated with amplifier A', control unit B' and stepping switch unit C'.

Normally closed contacts 85 are in series with the Operating circuit of electro-magnet 5|]HL of Stepping switch C', while normally closed contacts 85a'are in series with electro-magnet 50 of Stepping switch C, this arrangement being such Vthat the operation of Stepping switch C will momentarily open the Operating circuit for Stepping switch C', and likewise the operation of Stepping switch C' will momentarily open the Operating circuit for Stepping switch C, so that only one Stepping switch may be in the operativeposition vat any given instant.

The arrangement shown follows uSual practice in the Stepping switch contact arrangement, it being understood that other arrangements may also be =practical and that any number of such Stepping SWitcheS, .together with the associated amplifiers and `control circuits, may be used and 'So arranged that only one of said Stepping vswitches may be operated at any given instant.

Referring now to 'Figure 2, an enlarged view is 'shown of the control electrodes, all reference numerals being the same as those used in connection with Figure 1. In addition to the detail disclosed by Figure 1, the insulating section 8| ...is clearly shown interposed between feedback ,55 sired registration means 41 for example, illumi- -electrode 4| `and vfeedback electrode Shield 40.

V'Connection 39 is connected to control grid 4 of electrodeand that Figure 2 is self-explanatory.

'Referring Vmore specifically Vto Figure 4, the 'same electrode structure is represented except .thatin ;Figure 4 the electrode is installed below 'the playing 'surface of 'playing'board 43, so as to present .a smooth and unbroken playing Surface ;82. The distance `X may be any value desired,

.a practic'al 'value being on the order of -312 inch,

it being understood that as the distance X is 'increased the sensitivity is decreased. However, 'for' a Small distance X, for example, on the order of zzinch, there is only a slight decrease in sensi- 'tivity and for a 'larger distance X, for example,

on the order -of 1/3 inch, circuit values'may be 'adiusted for increased sensitivity.

Referring now to Figure 3 a skeleton view of the eleotrode structure is represented where the broken lines 83 diagrammatically represent the electric field linesA associated with the control electrode structure, it being understood that such electric field lines do not necessarily have a circular shape as represented by the broken lines 83. For a condition where playing ball 42 is outside of the electric field 83, very little energy is fed back from electrode 4| to electrode 46, due to the effects of shield 44 and shield 49. The actual amount of feedback energy for this condition may be Controlled by adjusting feedback control 34 and, in any event, the steady DC control voltage developed from any such residual feedback will not act to trigger gas filled discharge tube 12, due to the continuous nature of such voltage.

Maximum sensitivity is realized when all values are so adjusted that minimum feedback exists between feedback electrode 4| and input electrode 46. However, the device is operative for any condition where the feedback relationship between feedback eleotrode 4| and input electrode 46 is less than maximum, maximum feedback as a steady state condition representing zero sensitivity.

Referring now to Figure 5 which is a skeleton view similar to Figure 3, except that playing ball 42 is now in the electric field, as represented by the broken lines 84. This electric field is now distorted by the momentary presence of playing ball 42, so that additional energy is transferred from feedback electrode 4| to input electrode 4B. If playing ball 42 is moving at any practical speed, this increase in feedback will result in a D. C. voltage pulse which will act to trigger gas filled discharge tube 12 and cause the passage of playing ball 42 to be suitably registered, as previously described in detaii.

The operation of the invention herein described is independent of the speed of travel of the playing ball, for any practical speed, is insensitive to the influence of external forces, is economical to construct and reliable in operation. Normally, close control of plate voltage is not necessary in order to produce reliable operation. The device as herein desoribed is sensitive only to the passage of a playing ball, or other object which may be used in carrying out the purposes of an amusement game of the class herein referred to, it being of no practical importance,

whether such object is metallic or non-metallic.

False registration cannot be caused by the effects of body capacity. The actual'effect of such body capacity is to lower the effect of feedback due to the additional shielding represented by such body capacity. However, this effect is not great enough, in any practical design, to cause failure of proper registration. By way of example, I have so adjusted circuit values that a D. C. peak voltage of 25 volts is necessary in order to produce ionization of gas filled discharge tube 12. For this condition, I have found that an average D. C. peak voltage of 250 volts is produced by the passage of a 1/2 inch steel ball traveling at 20 feet per second. A maximum possible eifect of body capacity may lower this instantaneous D. C. peak voltage to a value on the order of 75 volts but this lowered value is still 300% greater than the value needed to cause ionization of gas filled discharge tube 12, and the minimum valueof 25 D. C. volts required is suificiently high that false operation is improbable from transients, voltage fiuctuations, etc.

I claim: 4

1. In an electronic control system including a registering means adapted to be activated by a control circuit responsive only to a control voltage in excess of a predetermined value, a pick-up electrode and a feed back electrode, an amplifier having an input circuit connected to the pick-11D electrode and an output circuit connected to the feed back electrode, means partially shielding the pick-up electrode from the feed back electrode to restrict the amount of energy feed back from the output circuit to the input circuit of the amplifier, adjustable means controlling the degree of feed back normally to prevent oscillation of the amplifier when no object is present in the field between said electrodes. the coupling between said electrodes being increased by the presence of an object in the vicinity of the electrodes sufficiently to cause said amplifier to oscillate, and means for supplying the control circuit with a control' voltage in excess of said pre-determned value from the increased voltage output of the oscillating amplifier when an object is present in said field.

2. In an electronic control system including registering means adapted to be activated by a control circuit responsive only to a control voltage in excess of a predetermined value, a pair of spaced external electrodes, an electronic amplifier having an input circuit connected to one of said electrodes and an output circuit connected to the other of said electrodes, means shielding at least one of said electrodes to restrictthe feed back from the output circuit to the input circuit of the amplifier substantially to prevent oscillation of said amplifier when no object is present in the field between said electrodes, the increase in energy feed back between said electrodes due to the presence of an object in the field between said electrodes causing said amplifier to oscillate, said control circuit including a gas-filled electronic tube normally non-conducting, a rectifier operatively connected to the output circuit of the oscillator, and means for supplying to the gas-filled tube a rectified voltage pulse from said rectifier in excess of the threshold voltage of saidv gas-filled tube when an object passes through the field between said electrodes.

STANLEY D. EILENBERGER.

REFEREN CES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,806,093 Sorensen May 19, 1931 2,130,123 Ebert Sept. 13, 1938 2,150.440 Hargreaves Mar. 14, 1939 2,181,388 Wells Nov, 28, 1939 2,182,336 Goldstine Dec. 5, 1939 2,l92,596 Durant Mar. 5, 1940 2,2l4,274 Glendenning Sept. 10, 1940 2,234,895 Cerveny et al Mar. 11, 1941 2,291,749 Nicolaus Aug. 4, 1942 2,305.661 Bancroft Dec. 22, 1942 2,318.169 La Rock May 4, 1943 2,319,786 Binks May 25, 1943 2320347 Brosseau June 1, 1943 2,337,132 Shaw Dec. 21, 1943 2,340,213 Ellsworth Jan. 25, 1944 FOREIGN PATENTS Number Country Date 494,995 Great Britain Nov. 4, 1938 

